BRIDGEPORT -- Representing personal injury clients was Joseph Haddad's boon. Now it may be his curse.

On Wednesday, it resulted in his bust.

Haddad, 65, who maintained a law office first in Trumbull and then Bridgeport, turned himself in to FBI agents holding a warrant for his arrest in connection with a $2.5 million insurance fraud involving medical treatment for motor vehicle accident victims. Haddad appeared before U.S. Magistrate Judge Holly B. Fitzsimmons and pleaded not guilty to conspiring to commit mail fraud and eight charges of mail fraud. Each of the charges carries a maximum 20-year prison term.

Haddad's arrest is the seventh in a 14-month undercover FBI investigation dubbed "Operation Running Man." The case, headed by FBI Special Agent Daniel Curtin, has netted four area chiropractors, a Monroe doctor and a former Bridgeport doctor.

Travelers, Metropolitan, Progressive, Esurance and Nationwide are among the insurers who claim they were defrauded in the scheme from December 2006 to February 2010.

The FBI infiltrated the operation with an undercover agent, who feigned injury, obtained treatment, recovered conversations and documented evidence.

The probe alleges that Haddad paid cash to individuals to find clients involved in motor vehicle accidents. Documents seized by the FBI indicate that Mark Kirshner, who owned and operated chiropractic offices in Bridgeport and Stamford and Midas Medical LLC, a diagnostic testing company, provided Haddad with at least $100,000 in cash as a finder's fees.

After meeting with the clients, Haddad allegedly would recommend they visit Francisco Carbone, a former doctor whose license was pulled by the state. Carbone fabricated injuries in reports and provided permanent disability ratings, often without examining the clients, according to the FBI. On occasion, the FBI said, he recommended that Dr. James W. Marshall, who operates Immediate Medical Care in Monroe, provide clients with narcotic pain prescriptions.

"The level of detail and orchestration alleged in this conspiracy to defraud automobile insurance companies is wrought with unadulterated greed and avarice," said Kimberly Mertz, head of FBI operations in Connecticut.

Following his arraignment, Haddad was released on a $150,000 non-surety bond. But not before Fitzsimmons heard two emotional recordings played by Assistant U.S. Attorney Christopher Schmeisser.

Schmeisser said the recordings were made after a man he identified as Haddad called a veteran's crisis center on Sept. 1, 2011, asking when it was "justified to kill an FBI agent."

The crisis center then called Norwalk Police, who in turn, contacted Haddad, Schmeisser told the judge. In that call, the man identified as Haddad told police the FBI had been harassing him for several years and threatened to put him in prison for the rest of his life.

"I just asked a question," the man was heard saying. "I was very upset. You would be too, if you were in my shoes."